The invention relates to a film scanner for optically scanning a film for obtaining a picture signal, which film is moved at a substantially constant speed.
A problem in such film scanners is that the image position in the electronic picture signal is not constant. The cause of this problem may reside in mechanical irregularities of the film, but also, for example in speed fluctuations.
Different methods of image position stabilization are known, which use, for example the film perforations for this purpose (DE-A-37 36 790), or the image boundaries of the film. A film scanning arrangement is known from British Patent Application GB-A-2,165,417 in which an image position correction is performed with reference to a comparison of successive images of a film. However, the problem of this method is that successive film images are not necessarily equal due to motions which are present in the image. It is true that it may be attempted to detect motion present in the image, but this will never be a completely successful operation.